You are correct, the pot does not set the center frequency, instead it is the 10k resistor in the gyrator, but the pot value does have an effect on the peaks and valleys, 100k giving a bit more range than the 10k.yes but capacitors are the same in both circuits.. i've checked it.. only pots are diferrent (10k vs 100k)
Out of the 5 important goals set above, the only one properly met by tubes is Infinite input impedance , all others fail miserably:The Ideal Op-amp
The IC Op-amp comes so close to ideal performance that it is useful to state the characteristics of an ideal amplifier without regard to what is inside the package.
Infinite voltage gain
Infinite input impedance
Zero output impedance
Zero input offset voltage (i.e., exactly zero out if zero in).